(1) Field of Invention
The present invention relates to a series of novel silicone isethionate polymers. These materials are surface active silicone compounds which are useful in a personal care and related applications, Specifically in the formulation of synthetic detergent bars, the so called syndet bars.
Since the compounds of the present invention are high molecular weight silicone polymers, they have a high degree of oxidative stability, even at elevated temperatures. In addition, these compounds are non volatile and non irritating to eyes and skin.
The compounds of the present invention are prepared by the reaction of the hydroxyl group on sodium isethionate with a carboxy silicone.
(2) Object of the Invention
It is the object of the present invention to provide a series of novel silicone isethionate polymers, which are exceptionally mild detergents and which are substantive to skin and hair. This substantivity results in superior softening, conditioning and antistatic properties.
It is another objective of the current invention to provide silicone isethionate derivatives which are nonirritating surface active agents. The compounds of the present invention have very low irritation values when applied to skin and eyes. Irritation is a major problem with traditional surfactants.
Application of the compounds of the invention can be from solvent, aqueous dispersion or solution, or applied neat in these process. It is anticipated that the effective conditioning concentration of the compound of this invention ranges from 0.1% to 25% by weight.
(3) Description of the Arts and Practices
Silicone oils (polydimethylsiloxane) have been known to be active at the surface of plastic, cellulosic and synthetic fibers as well as paper. Despite the fact that they are lubricants that are stable to oxidation, their high cost and lack of durability has made them cost prohibitive in most application areas. Silicone oils need to be emulsified prior to application. This requires high pressure equipment, surface active agents and generally results in a milky emulsion. Emulsions have experienced stability problems both in terms of freeze thaw instability and upon heating. This has resulted in minimal acceptance of them in commercial products.
The low efficiency of silicone oils is due to the fact that the oil is very water insoluble. Emulsions are generally prepared which contain silicone dispersed in micelles. While this method of application is easier for processing, much of the oil stays in the surfactant micelle and never gets deposited on the fiber. That which does deposit on the fiber surface remains there by hydrophobic binding, not ionic bonding. Since the polydimethylsiloxane is not bonded the effect is very transient. The product is removed with one washing. Fatty sodium Isethionate derivatives known to those skilled in the art. Sodium isethionate conforms to the following structure: EQU HO--(CH.sub.2).sub.2 --SO3M
wherein M is a metal ion preferably an alkali metal such as sodium, potassium, ammonium or lithium.
U.S. Pat. No. 4,515,721 issued to Login in May of 1985 teaches one method of producing fatty isethionates. While this patent discloses a new process for preparation of fatty products, there was no attempt to incorporate silicone into compound. Consequently, the unique softening and substantivity properties achieved using the compounds of the present invention are not realized with the above technologies.